Sensitivity of cortical movement representations to motor experience: evidence that skill learning but not strength training induces cortical reorganization.

The topography of forelimb movement representations within the rat motor cortex was examined following forelimb strength training. Adult male rats were allocated to either a Power Reaching, Control Reaching or Non-Reaching Condition. Power Reaching rats were trained to grasp and break progressively larger bundles of dried pasta strands with their preferred forelimb. Control Reaching animals were trained to break a single pasta strand and Non-Reaching animals were not trained. Power Reaching animals exhibited a progressive increase in the maximal size of the pasta bundle that could be retrieved during a 30-day training period. Kinematic analyses showed that this improvement was not due to a change in reaching strategy. Intracortical microelectrode stimulation was used to derive maps of forelimb movement representations within the motor cortex of all animals following training. In comparison to Non-Reaching animals, both Power Reaching and Control Reaching animals exhibited a significant increase in the proportion of motor cortex occupied by distal forelimb movement representations (wrist/digit) and a decrease in the proportion of proximal representations (elbow/shoulder). These results demonstrate that the development of skilled forelimb movements, but not increased forelimb strength, was associated with a reorganization of forelimb movement representations within motor cortex.

Percutaneous rotational thrombectomy reduces acute reocclusion in an animal model of acute coronary thrombosis.

This study was designed to compare acute reocclusion rates after treatment of acute coronary thrombosis with a percutaneous thrombectomy device or standard balloon angioplasty. Our group has previously reported on the rationale and development of a mechanical device for the treatment of intra-arterial thrombosis. This device removes fibrin from thrombus, allowing for dissolution of the cellular elements of the thrombus. Theoretically, thrombus removal (as opposed to displacement) might result in a lower rate of acute rethrombosis. The present study utilizes the device percutaneously in the coronary arteries of closed chest swine and compares recanalization and reocclusion rates with standard balloon angioplasty. Twenty-six animals with total thrombotic coronary occlusions were treated; 13 with each device. Reocclusion rates with the thrombectomy device were significantly reduced at 60 min and 120 min after recanalization (p < 0.02), and the mean time to reocclusion was prolonged by 45 min (p = 0.07). Technical problems included poor handling characteristics in early prototypes and stress fractures secondary to improper use. Changes in catheter design and operator protocols have largely eliminated these problems. We conclude that this study demonstrates the feasibility of percutaneous mechanical thrombectomy in the coronary arteries and that reocclusion rates after recanalization of thrombotic occlusions compare favorably to standard angioplasty.

Pneumatosis intestinalis as a complication of jejunoileal bypass.

Four patients with pneumatosis intestinalis involving the unbypassed functioning bowel after jejunoileal bypass for obesity are reported. Previous publications of pneumatosis intestinalis after jejunoileal bypass discussed involvement only of the bypassed defunctionalized bowel. Symptomatology can range from mild to severe. The treatment of pneumatosis intestinalis is conservative. The specific etiology of the pneumatosis in this group of patients is not known.